Electrical Cable

ABSTRACT

An electrical cable includes a first conductor assembly having a first inner conductor and a first insulator engaging and surrounding a surface of the first inner conductor and a second conductor assembly having a second inner conductor and a second insulator engaging and surrounding a surface of the second inner conductor. The electrical cable includes a non-conductive buffer layer surrounding the conductor assemblies having an inner surface engaging the insulators and a conductive shield layer engaging and surrounding an outer surface of the non-conductive buffer layer and providing electrical shielding for the conductor assemblies. An outer jacket engages and surrounds the conductive shield layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending, commonlyassigned U.S. application Ser. No. 15/591,579, filed May 10, 2017, theentire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter herein relates generally to electrical cables thatprovide shielding around signal conductors.

Electrical cables are used in high-speed data transmission applications,such as for high definition video transmission. For example, electricalcables may be used in a video endoscope device for video endoscopy. Someelectrical cables use twisted pairs for high speed digital signalpropagation. For quality signal integrity, the signal path needsadequate bandwidth as higher bandwidth allows for faster data rates. Insome applications, electromagnetic interference (EMI) and/or radiofrequency interference (RFI) are concerns so the electrical cables areshielded to protect against interference from environmental sources ofEMI/RFI. However, in shielded twisted pair designs, the shield oftenlimits the performance of the electrical cable as the shield in generaldegrades the bandwidth of the supported signal by introducing additionalattenuation.

To reduce the negative impact of the shield on the signal transmission,some cable designs increase the thickness of the insulator surroundingthe signal conductors. However, increasing the thickness of theinsulator increases the overall diameter of the cable. Additionally, thematerial of the insulator may be relatively rigid, making the cable lessflexible as the thickness of the insulator is increased.

A need remains for an electrical cable having improved mechanical andelectrical performance.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, an electrical cable is provided including a firstconductor assembly and a second conductor assembly that extend along alength of the electrical cable. The first conductor assembly includes afirst inner conductor and a first insulator engaging and surrounding asurface of the first inner conductor. The second conductor assemblyincludes a second inner conductor and a second insulator engaging andsurrounding a surface of the second inner conductor. The electricalcable includes a non-conductive, low dielectric loss, buffer layersurrounding the first and second conductor assemblies having an innersurface engaging the first and second insulators and an outer surfaceopposite the inner surface. The electrical cable includes a conductiveshield layer engaging and surrounding the outer surface of thenon-conductive buffer layer and providing electrical shielding for thefirst and second conductor assemblies. The electrical cable includes anouter jacket engaging and surrounding the conductive shield layer.

In another embodiment, an electrical cable is provided including a firstconductor assembly and a second conductor assembly that extend along alength of the electrical cable. The first conductor assembly includes afirst inner conductor and a first insulator engaging and surrounding asurface of the first inner conductor. The second conductor assemblyincludes a second inner conductor and a second insulator engaging andsurrounding a surface of the second inner conductor. The electricalcable includes a non-conductive low dielectric loss, buffer layersurrounding the first and second conductor assemblies. Thenon-conductive buffer layer includes braided strands of non-conductivematerial. The non-conductive buffer layer has an inner surface engagingthe first and second insulators and an outer surface opposite the innersurface. The electrical cable includes a conductive shield layerengaging and surrounding the outer surface of the non-conductive bufferlayer. The conductive shield layer includes braided strands ofconductive material and provides electrical shielding for the first andsecond conductor assemblies. The electrical cable includes an outerjacket engaging and surrounding the conductive shield layer.

In a further embodiment, an electrical cable is provided for a videoendoscope device having a camera and a display that includes a firstconductor assembly that extends along a length of the electrical cableconfigured to be electrically connected to the camera and the display.The first conductor assembly includes a first inner conductor and afirst insulator engaging and surrounding a surface of the first innerconductor. The electrical cable includes a second conductor assemblyadjacent the first conductor assembly along the length of the electricalcable configured to be electrically connected to the camera and thedisplay. The second conductor assembly includes a second inner conductorand a second insulator engaging and surrounding a surface of the secondinner conductor. The electrical cable includes a non-conductive lowdielectric loss, buffer layer surrounding the first and second conductorassemblies having an inner surface engaging the first and secondinsulators and an outer surface opposite the inner surface. Theelectrical cable includes a conductive shield layer engaging andsurrounding the outer surface of the non-conductive buffer layer andproviding electrical shielding for the first and second conductorassemblies. The electrical cable includes an outer jacket engaging andsurrounding the conductive shield layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system using an electrical cable formedin accordance with an embodiment to connect a first component and asecond component.

FIG. 2 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 3 is a perspective view of the electrical cable sectioned to showvarious elements of the electrical cable.

FIG. 4 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 5 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 6 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 7 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 8 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 9 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

FIG. 10 is a cross-sectional view of the electrical cable in accordancewith an exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic view of a system 10 using an electrical cable 100formed in accordance with an embodiment to connect a first component 12and a second component 14. The electrical cable 100 may be used for highspeed data transmission between the first and second components 12, 14.The electrical cable 100 may be used as a high-frequency signaltransmitter. The electrical cable 100 provides electrical shielding forthe data transmission lines between the first and second components 12,14.

In the illustrated embodiment, the system 10 includes a video endoscopedevice 20 with the electrical cable 100 connected between a camera 12defining the first component 12 at a first end 22 of the electricalcable 100 and a display 14 defining the second component 14 and a secondend 24 of the electrical cable 100. The video endoscope device 20 mayinclude other components in alternative embodiments. The electricalcable 100 may be used to transmit video signals, such as in medicalimaging applications for surgical endoscopy. In other variousembodiments, the electrical cable 100 may be used with other types ofdevices and is not intended to be limited to the video endoscope device20. For example, the electrical cable 100 may be used in a datacommunication application, such as electrical switches, routers, and/orhost bus adapters.

FIG. 2 is a cross-sectional view of the electrical cable 100 inaccordance with an exemplary embodiment. FIG. 3 is a perspective view ofthe electrical cable 100 sectioned to show various elements of theelectrical cable 100. The electrical cable 100 includes at least oneconductor assembly, such as a first conductor assembly 102 and a secondconductor assembly 104 as in the illustrated embodiment. In an exemplaryembodiment, the conductor assemblies 102, 104 form a twisted pair wherethe conductor assemblies 102, 104 are twisted or wound helically aroundeach other along the length of the electrical cable 100.

The conductor assemblies 102, 104 are held in a core of the electricalcable 100 within an outer jacket 106. The outer jacket 106 surrounds theconductor assemblies 102, 104 along the length of the electrical cable100. In FIG. 3, the conductor assemblies 102, 104 are shown protrudingfrom the outer jacket 106 for clarity in order to illustrate the variouscomponents of the electrical cable 100 that would otherwise beobstructed by the outer jacket 106. It is recognized, however, that theouter jacket 106 may be stripped away from the conductor assemblies 102,104 at or both ends 22, 24 of the electrical cable 100, for example, toallow for the conductor assemblies 102, 104 to terminate to thecomponents 12, 14.

In an exemplary embodiment, the electrical cable 100 includes aconductive shield layer 108 inside the outer jacket 106 that provideselectrical shielding for the conductor assemblies 102, 104. In anexemplary embodiment, the electrical cable 100 includes a non-conductivebuffer layer 150 between the conductive shield layer 108 and theconductor assemblies 102, 104. For example, the non-conductive bufferlayer 150 surrounds the first and second conductor assemblies 102, 104and provides a buffer between the conductor assemblies 102, 104 and theconductive shield layer 108, such as to control spacing between theconductor assemblies 102, 104 and the conductive shield layer 108 and/orto control an impedance of the electrical cable 100. The shield layer108 is electromagnetically coupled to the first and second conductorassemblies 102, 104 through the non-conductive buffer layer 150.

The outer jacket 106 is formed of at least one dielectric material, suchas one or more polymers (for example, polyethylene, polypropylene,polytetrafluoroethylene, or the like). The outer jacket 106 is notconductive, and is used to insulate the shield layer 108 from objectsoutside of the electrical cable 100. The outer jacket 106 also protectsthe shield layer 108 and the other internal components of the electricalcable 100 from mechanical forces, contaminants, and elements (such asfluctuating temperature and humidity). Optionally, the outer jacket 106may be extruded or otherwise molded around the shield layer 108.Alternatively, the outer jacket 106 may be wrapped around the shieldlayer 108 or heat shrunk around the shield layer 108.

The first conductor assembly 102 includes a first inner conductor 110that is configured to convey data signals, such as video signals and afirst insulator 112 surrounding the first inner conductor 110. The innerconductor 110 and insulator 112 extend longitudinally along the lengthof the electrical cable 100. The inner conductor 110 is formed of aconductive material, such as metal. The inner conductor 110 may be solidor composed of a combination of multiple strands wound together. Theinsulator 112 engages and surrounds a surface 114 of the inner conductor110. As used herein, two components are in “engagement” when there isdirect physical contact between the two components. The insulator 112 isformed of a dielectric material, such as fluorinated ethylene propylene(FEP) for example. The insulator 112 may be extruded with the firstinner conductor 110. The insulator 112 is configured to maintainseparation between the inner conductor 110 and other components, such asa shield of the electrical cable 100 or from the conductor of the secondconductor assembly 104 to electrically insulate the inner conductor 110preventing an electrical short. The size and/or shape of the innerconductor 110, the size and/or shape of the insulator 112, and therelative positions of the inner conductor 110 and the insulator 112 maybe modified or selected in order to attain a particular impedance forthe electrical cable 100.

The second conductor assembly 104 includes a second inner conductor 120that is configured to convey data signals, such as video signals and asecond insulator 122 surrounding the second inner conductor 120. Theinner conductor 120 and insulator 122 extend longitudinally along thelength of the electrical cable 100. The inner conductor 120 is formed ofa conductive material, such as metal. The inner conductor 120 may besolid or composed of a combination of multiple strands wound together.The insulator 122 engages and surrounds a surface 124 of the innerconductor 120. The insulator 122 is formed of a dielectric material. Theinsulator 122 is configured to maintain separation between the innerconductor 120 and other components, such as a shield of the electricalcable 100 or from the first inner conductor 110 of the first conductorassembly 102 to electrically insulate the inner conductor 120 preventingan electrical short. The size and/or shape of the inner conductor 120,the size and/or shape of the insulator 122, and the relative positionsof the inner conductor 120 and the insulator 122 may be modified orselected in order to attain a particular impedance for the electricalcable 100. Optionally, the size and/or shape of the inner conductors110, 120 may be identical and the size and/or shape of the insulators112, 122 may be identical. In other various embodiments, the first andsecond insulators 122 may be integral, such as being co-molded aroundthe inner conductors 110, 120.

The first and second insulators 112 are surrounded by the non-conductivebuffer layer 150 and the conductive shield layer 108. The conductiveshield layer 108 is formed of a conductive material, such as a metalmaterial. In an exemplary embodiment, the conductive shield layer 108 isa braided shield including braided strands of conductive material. Forexample, the shield layer 108 may include silver plated copper braidedstrands. The braided strands wrap helically around the core of theelectrical cable 100. The conductive shield layer 108 is configured toprovide electrical shielding for the pair of conductor assemblies 102,104 from external sources of EMI/RFI interference. The conductive shieldlayer 108 is configured to provide flexibility for the electrical cable100, allowing the electrical cable 100 to bend and flex whilemaintaining shielding integrity. Other types of shields may be providedin alternative embodiments, such as conductive foils wrapped helicallyaround the core of the electrical cable 100.

The outer jacket 106 surrounds and engages an outer surface 130 of theshield layer 108. In the illustrated embodiment, the outer jacket 106engages the shield layer 108 along substantially the entire periphery ofthe shield layer 108. An inner surface 132 of the shield layer 108surrounds and engages the non-conductive buffer layer 150. The innersurface 132 may engage the non-conductive buffer layer 150 alongsubstantially the entire periphery of the non-conductive buffer layer150. In an embodiment, the cross-sectional shape of the shield layer 108may be geometrically similar to the cross-sectional shape of thenon-conductive buffer layer 150. The term “geometrically similar” isused to mean that two objects have the same shape, although differentsizes, such that one object is a scaled relative to the other object.For example, as shown in FIG. 2, the shield layer 108 has a generallycircular shape along the cross-section and the non-conductive bufferlayer 150 has a generally circular shape along the cross-section;however, other shapes are possible in alternative embodiments, such asan elliptical or oval shape along the cross-section

The non-conductive buffer layer 150 has an inner surface 152 and anouter surface 154. The inner surface 152 engages and surrounds the firstand second insulators 112, 122 of the first and second conductorassemblies 102, 104. The outer surface 154 is opposite the inner surface152 and faces the inner surface 132 of the shield layer 108. Thenon-conductive buffer layer 150 is formed of a non-conductive material,such as a polymer material. The non-conductive buffer layer 150 providesa layer of insulation having a low dielectric constant between theconductor assemblies 102, 104 and the shield layer 108. In variousembodiments, the non-conductive buffer layer 150 is manufactured from anaromatic polymer material, such as an aromatic polyamide material, anaromatic polyester material, and the like. The non-conductive bufferlayer 150 may be manufactured from a poly paraphenylene terephthalamidematerial such as or similar to Kevlar®, an aliphatic or semi-aromaticpolyamide such as or similar to nylon, a melt spun liquid crystalpolymer such as or similar to Vectran®, and the like.

In an exemplary embodiment, the non-conductive buffer layer 150 is abraided layer including braided strands of non-conductive material.Braiding of the non-conductive buffer layer 150 may increase themechanical strength of the buffer layer 150. The non-conductive strandsare braided around the core of the electrical cable 100 and may wraphelically around the core. The non-conductive buffer layer 150 may beporous to air. For example, air may be present between and around thevarious braided strands. As such, air dielectric is present around thefirst and second insulators 112, 122, which may affect the dielectricconstant of the electrical cable 100 and the impedance of the electricalcable 100. In an exemplary embodiment, the non-conductive buffer layer150 has M number of picks of braided strands of non-conductive materialand the conductive shield layer 108 has N number of picks of braidedstrands of conductive material different than the M number of picks ofbraided strands of non-conductive material. For example, thenon-conductive buffer layer 150 may have between approximately 15 and 30picks of braided strands of non-conductive material and the conductiveshield layer 108 may have between approximately 20 and 40 picks ofbraided strands of conductive material. In an exemplary embodiment, thenon-conductive buffer layer 150 may have approximately 20 picks ofbraided strands of non-conductive material and the conductive shieldlayer 108 may have approximately 25 picks of braided strands ofconductive material. The number of picks of braided strands may affectthe flexibility of the layers, the pull strength of the layers, theshield effectiveness of the conductive shield layer 108, the dielectricconstant of the non-conductive buffer layer 150, and the like. Othertypes of buffer layers may be provided in alternative embodiments, suchas non-conductive tapes or foils wrapped helically around the core ofthe electrical cable 100 and/or non-conductive fillers.

The non-conductive buffer layer 150, in an embodiment, has a uniformradial thickness 156 between the inner surface 152 and the outer surface154. The radial thickness 156 controls the positioning of the shieldlayer 108 relative to the first and second conductor assemblies 102,104. By having a uniform radial thickness, the shield layer 108 ispositioned a constant radial distance from the inner conductors 110, 120to provide consistent electrical properties along the length of theelectrical cable 100. For example, the distance from the inner conductor110 to the shield layer 108 at any location along the length may beapproximately equal to the distance from the inner conductor 120 to theshield layer 108 at any location along the length. Providing a uniformradial thickness 156 controls relative positions of the shield layer 108and the conductor assemblies 102, 104 to support the signal integrity byreducing attenuation due to irregularities and/or discontinuities in theelectrical shielding. In an exemplary embodiment, the radial thickness156 is significantly less than a radial thickness of the insulator 112or the insulator 122, such as less than half the radial thickness of theinsulator 112 or the insulator 122 such that the non-conductive bufferlayer 150 has minimal impact on the overall diameter of the electricalcable 100.

In an exemplary embodiment, the non-conductive buffer layer 150 onlyengages a portion of the first insulator 112 and a portion of the secondinsulator 122 along the lengths thereof. For example, the inner surface152 engages the first insulator 112 along a minority of a circumferenceof the first insulator 112 and the inner surface 152 engages the secondinsulator 122 along a minority of a circumference of the secondinsulator 122. However, the non-conductive buffer layer 150 maintainsthe spacing of the shield layer 108 to the first insulator 112 and tothe second insulator 122, and thus to the first inner conductor 110 andthe second conductor 120, respectively. The non-conductive buffer layer150 increases the distance between the conductors 110, 120 and theshield layer 108 reducing the negative impact of the shield layer 108 onthe signal integrity of the electrical cable 100. For example, thepresence of the non-conductive buffer layer 150 may reduce the impact ofthe shield layer 108 by maximizing differential mode of signalpropagation. The presence of the non-conductive buffer layer 150 mayimprove attenuation in the signal conductors from the shield layer 108.The presence of the non-conductive buffer layer 150 may increase thebandwidth of the electrical cable 100 allowing faster data rates to betransmitted by the electrical cable 100.

In an exemplary embodiment, the non-conductive buffer layer 150 hasgreater flexibility per thickness than the material of the first andsecond insulators 112, 122. As such, by using the non-conductive bufferlayer 150, as opposed to increasing the thicknesses of the insulators112, 122, the flexibility of the electrical cable 100 for a given cablediameter may be increased and/or the diameter of the electrical cable100 may be decreased while achieving similar flexibilitycharacteristics. The electrical cable 100 may be limper than cableshaving thicker insulators 112, 122, making the electrical cable 100better suited for some applications, such as surgical endoscopy. In anexemplary embodiment, the non-conductive buffer layer 150 has increasedpull strength compared to the material of the first and secondinsulators 112, 122, which may allow the electrical cable 100 to bebetter adapted for some applications, such as surgical endoscopy, ascompared to electrical cables that do not utilize the non-conductivebuffer layer 150.

In an exemplary embodiment, the electrical cable 100 is provided withouta metal foil layer wrapped around the core. Foil layers tend to add costand weight to electrical cables. Additionally, foil layers makeelectrical cables less flexible and tend to degrade over time, such asdue to cracking or ripping as the electrical cable is bent and flexedduring use. The non-conductive buffer layer 150 is used to providespacing between the conductor assemblies 102, 104 and the shield layer108 to enhance the signal integrity of the conductor assemblies 102,104. The non-conductive buffer layer 150 is flexible allowing theelectrical cable 100 to be more limp and appropriate for use in someapplications, such as video endoscopy. In an exemplary embodiment, thenon-conductive buffer layer 150 is braided and manufactured from amaterial having high pull strength characteristics, which may improvethe reliability and useful life of the electrical cable.

FIG. 4 is a cross-sectional view of the electrical cable 100 inaccordance with an exemplary embodiment. FIG. 5 is a cross-sectionalview of the electrical cable 100 in accordance with an exemplaryembodiment. FIG. 6 is a cross-sectional view of the electrical cable 100in accordance with an exemplary embodiment. In the embodiments shown inFIGS. 4-6, the electrical cable 100 includes the first conductorassembly 102 and the second conductor assembly 104 and additionallyincludes a third conductor assembly 202 and a fourth conductor assembly204. The first and second conductor assemblies 102, 104 form a firsttwisted pair 206 and the third and fourth conductor assemblies 202, 204form a second twisted pair 208.

The non-conductive buffer layer 150 surrounds both twisted pairs 206,208 of conductor assemblies. The shield layer 108 surrounds thenon-conductive buffer layer 150 and the outer jacket 106 surrounds theshield layer 108. Other layers or additional twisted pairs may beprovided in other alternative embodiments.

The third conductor assembly 202 includes a third inner conductor 210that is configured to convey data signals, such as video signals and athird insulator 212 surrounding the third inner conductor 210. The innerconductor 210 and insulator 212 extend longitudinally along the lengthof the electrical cable 100. The inner conductor 210 is formed of aconductive material, such as metal. The insulator 212 engages andsurrounds a surface 214 of the inner conductor 210. The insulator 212 isconfigured to maintain separation between the inner conductor 210 andother components, such as the non-conductive buffer layer 150, theshield layer 108 and/or from other conductors to electrically insulatethe inner conductor 210 preventing an electrical short.

The fourth conductor assembly 204 includes a fourth inner conductor 220that is configured to convey data signals, such as video signals and afourth insulator 222 surrounding the fourth inner conductor 220. Theinner conductor 220 and insulator 222 extend longitudinally along thelength of the electrical cable 100. The inner conductor 220 is formed ofa conductive material, such as metal. The insulator 222 engages andsurrounds a surface 224 of the inner conductor 220. The insulator 222 isformed of a dielectric material. The insulator 222 is configured tomaintain separation between the inner conductor 220 and othercomponents, such as the non-conductive buffer layer 150, the shieldlayer 108 and/or from other conductors to electrically insulate theinner conductor 210 preventing an electrical short.

The inner surface 152 of the non-conductive buffer layer 150 engages andsurrounds the first and second insulators 112, 122 of the first andsecond conductor assemblies 102, 104 and the third and fourth insulators212, 222 of the third and fourth conductor assemblies 202, 204. Theuniform radial thickness 156 of the non-conductive buffer layer 150controls the positioning of the shield layer 108 relative to theconductor assemblies 102, 104, 202, 204. For example, the non-conductivebuffer layer 150 generally positions the shield layer 108 a constantradial distance from the inner conductors 110, 120, 210, 220 to provideconsistent electrical properties along the length of the electricalcable 100. As the twisted pairs 206, 208 are twisted along the length ofthe electrical cable 100, there may be sections of the conductorassemblies 102, 104, 202, 204 that do not engage the non-conductivebuffer layer 150. For example, FIG. 4 illustrates the third conductorassembly 202 positioned in the core such that the non-conductive bufferlayer 150 is not touching the third insulator 212 and FIG. 5 illustratesthe first conductor assembly 102 positioned in the core such that thenon-conductive buffer layer 150 is not engaging the first insulator 212;however, along other portions, the first and third insulators 112, 212the engages the non-conductive buffer layer 150. FIG. 6 illustrates thenon-conductive buffer layer 150 engaging all four of the insulators 112,122, 212, 222. As such, generally along the length of the electricalcable 100, the distances from the inner conductors 110, 120, 210, 220 tothe shield layer 108 are approximately equal and consistent.

FIG. 7 is a cross-sectional view of the electrical cable 100 inaccordance with an exemplary embodiment. FIG. 8 is a cross-sectionalview of the electrical cable 100 in accordance with an exemplaryembodiment. FIG. 9 is a cross-sectional view of the electrical cable 100in accordance with an exemplary embodiment. In the embodiments shown inFIGS. 7-9, the electrical cable 100 includes the first twisted pair 206having the conductor assemblies 102, 104 and the second twisted pair 208having the conductor assemblies 202, 204.

In an exemplary embodiment, a first non-conductive buffer layer 250surrounds the first twisted pair 206 and a second non-conductive bufferlayer 252 surrounds the second twisted pair 208. The firstnon-conductive buffer layer 250 engages and surrounds the first andsecond insulators 112, 122 of the first and second conductor assemblies102, 104. For example, an inner surface 270 of the first non-conductivebuffer layer 250 engages and surrounds the first and second insulators112, 122. The second non-conductive buffer layer 250 engages andsurrounds the third and fourth insulators 212, 222 of the third andfourth conductor assemblies 202, 204. For example, an inner surface 280of the second non-conductive buffer layer 252 engages and surrounds thethird and fourth insulators 212, 222. The shield layer 108 surrounds thenon-conductive buffer layers 250, 252. The outer jacket 106 surroundsthe shield layer 108. Other layers or additional twisted pairs may beprovided in other alternative embodiments.

The uniform radial thickness of the first non-conductive buffer layer250 controls the positioning of the shield layer 108 relative to theconductor assemblies 102, 104 of the first twisted pair 206. The uniformradial thickness of the second non-conductive buffer layer 252 controlsthe positioning of the shield layer 108 relative to the conductorassemblies 202, 204 of the second twisted pair 208.

FIG. 10 is a cross-sectional view of the electrical cable 100 inaccordance with an exemplary embodiment. The electrical cable 100includes the first twisted pair 206 having the conductor assemblies 102,104 and the second twisted pair 208 having the conductor assemblies 202,204.

In an exemplary embodiment, the first non-conductive buffer layer 250engages and surrounds the first and second insulators 112, 122 of thefirst and second conductor assemblies 102, 104 of the first twisted pair206 and a first conductive shield layer 260 surrounds the firstnon-conductive buffer layer 250. For example, an inner surface 270 ofthe first non-conductive buffer layer 250 engages and surrounds thefirst and second insulators 112, 122 and an inner surface 272 of thefirst conductive shield layer 260 engages an outer surface 274 of thefirst non-conductive buffer layer 250. The second non-conductive bufferlayer 252 engages and surrounds the third and fourth insulators 212, 222of the third and fourth conductor assemblies 202, 204 of the secondtwisted pair 208 and a second conductive shield layer 262 surrounds thesecond non-conductive buffer layer 252. For example, an inner surface280 of the second non-conductive buffer layer 252 engages and surroundsthe third and fourth insulators 212, 222 and an inner surface 282 of thesecond conductive shield layer 262 engages an outer surface 284 of thesecond non-conductive buffer layer 252. The outer jacket 106 surroundsthe first and second conductive shield layers 260, 262. Other layers oradditional twisted pairs may be provided in other alternativeembodiments.

The uniform radial thickness of the first non-conductive buffer layer250 controls the positioning of the first shield layer 260 relative tothe conductor assemblies 102, 104 of the first twisted pair 206. Theuniform radial thickness of the second non-conductive buffer layer 252controls the positioning of the second shield layer 262 relative to theconductor assemblies 202, 204 of the second twisted pair 208.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from its scope. Dimensions, types of materials,orientations of the various components, and the number and positions ofthe various components described herein are intended to defineparameters of certain embodiments, and are by no means limiting and aremerely exemplary embodiments. Many other embodiments and modificationswithin the spirit and scope of the claims will be apparent to those ofskill in the art upon reviewing the above description. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Moreover, in the following claims, theterms “first,” “second,” and “third,” etc. are used merely as labels,and are not intended to impose numerical requirements on their objects.Further, the limitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112(f), unless and until such claim limitations expresslyuse the phrase “means for” followed by a statement of function void offurther structure.

What is claimed is:
 1. An electrical cable comprising: a first conductorassembly that extends along a length of the electrical cable, the firstconductor assembly comprising a first inner conductor and a firstinsulator engaging and surrounding a surface of the first innerconductor; a second conductor assembly adjacent the first conductorassembly along the length of the electrical cable, the second conductorassembly comprising a second inner conductor and a second insulatorengaging and surrounding a surface of the second inner conductor; anon-conductive buffer layer surrounding the first and second conductorassemblies, the non-conductive buffer layer having an inner surfaceengaging the first and second insulators and an outer surface oppositethe inner surface; a conductive shield layer engaging and surroundingthe outer surface of the non-conductive buffer layer, the shield layerproviding electrical shielding for the first and second conductorassemblies; and an outer jacket engaging and surrounding the conductiveshield layer.
 2. The electrical cable of claim 1, wherein thenon-conductive buffer layer comprises braided strands of non-conductivematerial.
 3. The electrical cable of claim 2, wherein the conductiveshield layer comprises braided strands of conductive material.
 4. Theelectrical cable of claim 3, wherein the non-conductive buffer layer hasM number of picks of braided strands of non-conductive material and theconductive shield layer has N number of picks of braided strands ofconductive material different than the M number of picks of braidedstrands of non-conductive material.
 5. The electrical cable of claim 1,wherein the first and second conductor assemblies are electricallyconnected to a camera at a first end of the electrical cable and thefirst and second conductor assemblies are electrically connected to acamera control unit at a second end of the electrical cable.
 6. Theelectrical cable of claim 1, wherein the shield layer has a uniformradial thickness around the outer perimeters of the first and secondinsulators.
 7. The electrical cable of claim 1, wherein thenon-conductive buffer layer has a uniform thickness between the innersurface and the outer surface to locate the conductive shield layer at auniform distance from the first and second conductor assemblies.
 8. Theelectrical cable of claim 1, wherein the non-conductive buffer layercomprises braided strands of aromatic polymer material.
 9. Theelectrical cable of claim 1, wherein the non-conductive buffer layer isporous to air.
 10. The electrical cable of claim 1, wherein thenon-conductive buffer layer has greater flexibility per thickness thanthe material of the first and second insulators.
 11. The electricalcable of claim 1, wherein the non-conductive buffer layer has increasedpull strength compared to the material of the first and secondinsulators.
 12. The electrical cable of claim 1, wherein thenon-conductive buffer layer is braided around the first and secondconductor assemblies.
 13. The electrical cable of claim 1, wherein thefirst and second conductor assemblies are twisted helically around eachother along the length of the electrical cable.
 14. The electrical cableof claim 1, wherein the inner surface engages the first insulator alonga minority of a circumference of the first insulator and the innersurface engages the second insulator along a minority of a circumferenceof the second insulator.
 15. The electrical cable of claim 1, furthercomprising a third conductor assembly that extends along the length ofthe electrical cable, the third conductor assembly comprising a thirdinner conductor and a third insulator engaging and surrounding a surfaceof the third inner conductor, and further comprising a fourth conductorassembly that extends along the length of the electrical cable, thefourth conductor assembly comprising a fourth inner conductor and afourth insulator engaging and surrounding a surface of the fourth innerconductor, the first and second conductor assemblies defining a firsttwisted pair, the third and fourth conductor assemblies defining asecond twisted pair, the non-conductive buffer layer surrounding thethird and fourth conductor assemblies such that the inner surfaceengages the third and fourth insulators, the conductive shield layerproviding electrical shielding for the third and fourth conductorassemblies.
 16. An electrical cable comprising: a first conductorassembly that extends along a length of the electrical cable, the firstconductor assembly comprising a first inner conductor and a firstinsulator engaging and surrounding a surface of the first innerconductor; a second conductor assembly adjacent the first conductorassembly along the length of the electrical cable, the second conductorassembly comprising a second inner conductor and a second insulatorengaging and surrounding a surface of the second inner conductor; anon-conductive buffer layer surrounding the first and second conductorassemblies, the non-conductive buffer layer comprising braided strandsof non-conductive material, the non-conductive buffer layer having aninner surface engaging the first and second insulators and an outersurface opposite the inner surface; a conductive shield layer engagingand surrounding the outer surface of the non-conductive buffer layer,the conductive shield layer comprising braided strands of conductivematerial, the shield layer providing electrical shielding for the firstand second conductor assemblies; and an outer jacket engaging andsurrounding the conductive shield layer.
 17. The electrical cable ofclaim 16, wherein the non-conductive buffer layer comprises braidedstrands of aromatic polymer material.
 18. An electrical cable for avideo endoscope device having a camera and a display, the electricalcable comprising: a first conductor assembly that extends along a lengthof the electrical cable configured to be electrically connected to thecamera and the display, the first conductor assembly comprising a firstinner conductor and a first insulator engaging and surrounding a surfaceof the first inner conductor; a second conductor assembly adjacent thefirst conductor assembly along the length of the electrical cableconfigured to be electrically connected to the camera and the display,the second conductor assembly comprising a second inner conductor and asecond insulator engaging and surrounding a surface of the second innerconductor; a non-conductive buffer layer surrounding the first andsecond conductor assemblies, the non-conductive buffer layer having aninner surface engaging the first and second insulators and an outersurface opposite the inner surface; a conductive shield layer engagingand surrounding the outer surface of the non-conductive buffer layer,the shield layer providing electrical shielding for the first and secondconductor assemblies; and an outer jacket engaging and surrounding theconductive shield layer.